Cocaine abuse and dependence disorders comprise a highly prevalent public health concern. Exposure to environmental cues associated with drug taking can elicit self-reports of drug craving and potentially relapse in abstinent human drug users. These behaviors develop as learned responses to drug-related stimuli, and there is evidence implicating the importance of glutamatergic neurotransmission in associative learning and the neurobiological processes that mediate drug-conditioned behaviors. Understanding drug-conditioned behaviors could provide insight to the neuro-behavioral processes underlying drug abuse and could lead to effective treatments for addictive disorders. The objectives of the proposed study are to establish conditions in which drug-seeking behavior will be maintained by conditioned reinforcers associated with cocaine, and to evaluate the effects of site selective NMDA receptor related agents on behavior maintained by cocaine-associated conditioned reinforcers in rats. To this aim, NMDA agents that bind to specific sites on the NMDA receptor complex, specifically the polyamine, glycine, competitive, and non-competitive binding sites will be evaluated. Examining the various site-selective modulators is important as some may have advantages over others. The results of this study could provide information relevant to medication development for treating cocaine abuse, as well as heightened understanding of the contributory roles of the modulatory site on the NMDA receptor complex.